The present invention relates in general to police radar detectors and, more particularly, to police radar detectors and methods of operating police radar detectors so that one or more portions of a swept spectrum of frequencies are investigated multiple times during each sweep through the swept spectrum of frequencies.
Police have used radar systems to monitor the speed of motor vehicles for many years. The radar frequencies currently used throughout the world include: the X band −10.50 gigahertz (Ghz) to 10.55 Ghz; the Ku band −13.40 to 13.50 Ghz; the K band −24.05 Ghz to 24.25 Ghz; and the Ka band −33.40 Ghz to 36.00 Ghz. To alert motorists of the presence of police radar, electromagnetic signals within these radar bands are monitored using a police radar detector which issues an audible and/or visual alert upon detection of a radar signal within one of the bands.
As technological improvements are made in police radar speed measuring equipment to avoid their detection by radar detectors, improvements are made in police radar detectors so that the improved police radar can be detected. For example, to limit the effectiveness of radar detectors, police radar systems were improved to operate in both a continuous transmit mode and an intermittent transmit mode. In the intermittent transmit mode, the operator manually triggers the police radar dependent upon several conditions including, for example, the number of approaching vehicles or perhaps an initial visual determination of the speed of a single approaching vehicle.
While the intermittent mode of operating police radar systems initially reduced the ability of radar detectors to detect their presence in some instances, improvements were made to the detectors so that most newer radar detectors are effective even for intermittent police radar operation.
One of the most recent improvements in police radar to prevent existing radar detectors from detecting their radar transmissions is what is referred to as “POP” mode operation of the police radar. When police radar systems are in the POP mode, short bursts of energy are emitted so that vehicle speeds can be measured in less than a tenth of a second, i.e., less than 100 ms. The short bursts of energy are typically not detected by conventional radar detectors that require a signal to be stable over at least one sweep of the radar frequency bands of interest with each sweep taking more than a tenth of a second, for example, around 160 ms.
Radar detector manufacturers thus need to develop improvements to their radar detectors so that they can consistently and accurately detect police radar operating in the POP mode.